When building an outdoor plant box, choosing the right fasteners is crucial for durability and stability. The best options include stainless steel screws, which resist rust and corrosion, and galvanized nails for added strength. For a more rustic look, consider using weather-resistant wood screws with coated finishes. Additionally, deck screws are excellent for securing heavy-duty plant boxes due to their deep threading and corrosion-resistant properties. Always opt for fasteners labeled "outdoor-grade" to ensure longevity against rain, sun, and temperature changes. By selecting the right materials, your plant box will remain sturdy and attractive for years to come.